JP2003142731A - Light emitting diode element and device thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emitting diode element wherein generation ratio of chip peeling is reduced, and to provide its mount method. SOLUTION: The device has a light emitting diode element body 120 wherein a clad layer, a light emitting layer and a clad layer are formed one by one on a GaAs substrate 121, a bonding side electrode 130 formed on the clad layer of an upper side of the body, and a mount side electrode 110 formed in a lower side of the light emitting diode element body 120. The mount side electrode consists of an Au deposit film 111, a first metallic film 112 laminated on the deposit film, a second metallic film 115 laminated on the first metallic film, an Au film 113 laminated on the second metallic film, and an AuSn film 114 laminated on the Au film. The second metallic film has a melting point higher than that of the AuSn film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode element, and more particularly to a light emitting diode element having an electrode structure suitable for mounting the light emitting diode element by alloy bonding and a mounting method thereof.

[0002]

2. Description of the Related Art FIG. 2 is a cross-sectional view showing a structure of a conventional light emitting diode element, showing a state of being mounted on a Cu frame by alloy bonding.

As shown in FIG. 1, the light emitting diode element body 220 includes an N type GaAs substrate 221 and an N type InGaA.
1P clad layer 222, P-type InGaAlP light emitting layer 22
3. A P-type InGaAlP clad layer 224 is sequentially laminated. The bonding side electrode 230 provided on the upper surface of the light emitting diode element body 220 is the P-type I
On the surface of the nGaAlP clad layer 224, an AuBe film 231, an Au film 232, a Mo film 233, A is formed by vapor deposition or the like.
The p-type InGaAlP is formed by sequentially stacking the u films 234.
An ohmic contact is obtained with the clad layer 224.

On the other hand, the mount side electrode provided on the lower surface of the light emitting diode element body 220 is an AuGe film 211 in which pure Au is doped with Ge as an impurity in order to obtain ohmic contact with the N-type GaAs substrate 221 of the light emitting diode element body 220. Build up. Then, for example, a Mo film and a pure Au film for protecting the Mo film are formed as a metal film for preventing Sn diffusion, and heat treatment is performed to form the ohmic alloy layer 21.
Form 2. After that, a pure Au film 213 for preventing the peeling of the AuSn film is formed by vapor deposition, and an AuSn film 214 for forming an alloyed connection with the metal frame 240 is formed on the outermost surface. The metal frame 240 is made of Cu whose surface is plated with Ag.
It is composed of plates.

[0005]

The conventional light emitting diode element body 220 is brought into contact with the metal frame 240, heat-treated and mounted by alloy bonding. The light emitting diode element body thus mounted is mounted. Two
There is a problem in that so-called chip peeling frequently occurs when 20 peels from the metal frame 240. In the conventional manufacturing process, such a chip peeling defect rate has reached 2-3%.

Therefore, the present invention has been made in view of the above problems.
It is an object of the present invention to provide a light emitting diode element which prevents a peeling phenomenon after mounting the light emitting diode element and a mounting method thereof.

[0007]

As a result of investigating the cause of chip separation in order to achieve the above object, as a result of heat treatment, Sn in the AuSn film 214 forming the electrode 210 on the mount side is adjacent to the pure Au film. Diffused into 213,
It has been found that since the entire pure Au film 213 is transformed into an AuSn film and melted, the adhesion at the interface with the Mo film adjacent to the pure Au film 213 on the opposite side is reduced, which causes a peeling phenomenon. Therefore, according to the present invention, by interposing the second metal film having a higher melting point than the AuSn film 214 between the pure Au film 213 and the Mo film, the AuSn film 214 to the Au film are removed from the AuSn film 214 in the heat treatment step at the time of alloy joining. The above problem is solved by preventing the adhesion to the Mo film, which is the first metal film, from being affected even if Sn diffuses and changes in quality in 213.

That is, the light emitting diode device of the present invention comprises a light emitting diode device body in which a clad layer, a light emitting layer and a clad layer are sequentially formed on a GaAs substrate, and a bonding side formed on the clad layer on the upper surface of the body. An electrode and a mount-side electrode formed on the lower surface of the light-emitting diode element body are provided, and the mount-side electrode is laminated with an Au-based deposit film for making ohmic contact with the GaAs substrate. The first metal film, the second metal film laminated on the first metal film, the Au film laminated on the second metal film, and the AuSn film laminated on the Au film. , The second metal film is the Au
It is characterized by having a melting point higher than that of the Sn film.

Further, in the light emitting diode element of the present invention, the impurity diffusion preventing metal film is Mo and the refractory metal film is an AuGe alloy film.

Further, the light emitting diode device of the present invention comprises a light emitting diode element having the above electrode structure and a metal frame to which the mount side electrode of the light emitting diode element is alloyed.

Further, the light emitting diode device of the present invention is characterized in that the metal frame is a Cu or Fe frame whose surface is Ag-plated.

[0012]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described below with reference to FIG. The figure shows a cross section of an InAlGaP red light emitting diode mounted on a frame. The light emitting diode element body 120 is similar to the conventional element body in that the N type InGaAlP clad layer 122, the P type InGaAlP light emitting layer 123, and P are formed on the N type GaAs substrate 121.
A type InGaAlP cladding layer 124 is sequentially laminated. A P-side electrode 130 on the bonding side is formed on the upper surface of the light emitting diode element body 120 as in the conventional case. That is, the AuBe film 131 and the pure Au film 13 are formed on the surface of the P-type InGaAlP cladding layer 124 by vapor deposition or the like.
2, Mo film 133 and pure Au film 134 are sequentially formed and heat-treated to form an ohmic contact electrode having a bondable surface.

Next, the mount side N-face electrode 1 mounted on the Ag-plated Cu or Fe frame 140.
As shown in FIG. 1, 10 is an N-type GaA formed by a vacuum evaporation method.
On the surface of the s substrate 121, an AuGe film 111 of 2000 Å is formed as an electrode for ohmic contact, a Mo film 112 of 1500 Å is formed as a metal film for preventing Sn diffusion, and then an AuGe film 115 of 2000 Å for improving electrode adhesion is formed.
Further, 3000 Å of Au film 113 for protecting the electrode surface is sequentially formed, and heat treatment is performed to form an ohmic contact layer at the interface between the GaAs substrate 121 and the AuGe film 111.

Then, again, the Au film 1000Å and the AuSn film 114 are sequentially deposited by 10000Å by the vacuum evaporation method to form the mount side N-face electrode 110. next,
The light emitting diode element formed as described above is heat-treated in a state where the AuSn film 114 of the mount-side N-face electrode 110 is in contact with the Ag-plated surface of the Cu or Fe frame 140, and the mounting step for alloying is completed to emit light. The diode device is completed.

As described above, according to the present invention,
The influence of the deterioration of the Au film 113 due to the diffusion of Sn from the AuSn film 214 caused by the heat treatment on the adhesion at the interface with the Mo film 112 has an effect on the aAuGe film having a high melting point interposed between the Mo film 112 and the Au film 113. It was possible to prevent the chip separation from occurring by 115. Further, in the measurement of the chip peel strength, the average was 80 g in the conventional electrode structure, but it was 150 g or more in the electrode having the structure according to the present invention, and the adhesion strength could be improved about twice.

[0016]

In the manufacture of the light emitting diode using the electrode structure of the present invention, the chip peeling defect occurrence rate is reduced to about 0.2%, which is about 1/10 of the defect occurrence rate in the conventional electrode structure.
It has been improved as follows.

[Brief description of drawings]

FIG. 1 is a sectional view showing a structure of a light emitting diode and an electrode according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a structure of a conventional light emitting diode and its electrode.

[Explanation of symbols]

110 ... N-side electrode on mount side, 111 ... AuGe film, 112 ... First metal film (Mo film), 113 ... Au film, 114 ... AuSn film, 115 ... Second metal film (AuGe film), 120 ... Light emitting diode element body 121 ... N-type GaAs substrate, 122 ... N-type InGaAlP clad layer, 123 ... P-type InGaAlp light-emitting layer, 124 ... P-type InGaAlP clad layer, 130 ... P-side electrode on bonding side, 140 ... Ag-plated metal (Cu or Fe)
flame.

Claims (4)

[Claims] 1. A light emitting diode element body in which a clad layer, a light emitting layer and a clad layer are sequentially formed on a GaAs substrate, a bonding side electrode formed on the clad layer on the upper surface of the body, and the light emitting diode element body. A mount-side electrode formed on the lower surface is provided, and the mount-side electrode includes an Au-based deposition film, a first metal film laminated on the deposition film, and a first metal film laminated on the first metal film. The second metal film, the Au film laminated on the second metal film, and the Au film.
A light-emitting diode device comprising an AuSn film laminated on the film, wherein the second metal film has a higher melting point than the AuSn film. 2. The light emitting diode device according to claim 1, wherein the first metal film is Mo and the second metal film is an AuGe alloy film. 3. A light emitting diode device comprising the light emitting diode element according to claim 1 and a metal frame to which the mount side electrode of the light emitting diode element is alloyed. 4. The light emitting diode device according to claim 3, wherein the metal frame is a Cu or Fe frame whose surface is Ag-plated.